Apparatus for concentrating food products



Aug. 21., 1962 E. MAYER 3,050,114

APPARATUS FOR CONCENTRATING FOOD PRODUCTS Filed Dec. 1, 1959 .i l ll li 5/ 46 J2 53 65 INVENTOR: E rn s 1" M at] er ATTORNEYS Unite tats This invention relates to, and has for its primary object, the provision of an improved device for concentrating liquefied food products.

More specifically, this invention was devised for use in canneries, in cooking and concentrating tomato products, as for example, in the making of tomato sauces. In general, such sauces are made by placing the tomatoes in liquefied pulp form into some sort of cooking appara tus and by then heating the batch to evaporate the necessary amount of water therefrom until the desired concentration is reached. One of the biggest problems in such concentrating is the overheating of any or all of the batch, for such overheating will cause discoloration of the tomato product which is detrimental to the taste and eye appeal of the final product.

The method of concentrating tomato products now used most extensively involves placing a batch of liquefied pulp into large kettles having heating coils therein, and circulating steam through the coils to heat the batch and drive out the desired amount of water. This method is not completely desirable because, for quantity production, the kettles must be kept quite full and it is difficult to agitate and circulate the entire batch within the kettle such that all parts of the batch come into contact with the heating coils for an equal length of time. As a consequence, the temperatures of the coils must be maintained relatively high so that heat can be transmitted through the batch to that portion thereof which will not come into contact with the coils. This leads to the danger that a portion of the batch will be overheated and burnt by prolonged contact with the coils and also that a por tion of the batch will be undercooked, and it has been found that in using such apparatus, careful attention must be given to the process to avoid these detrimental possibilities.

Such cooking devices have also been used in a continuous cooking method wherein uncooked pulp is constantly added and cooked, concentrated pulp is constantly withdrawn. This method has not proven too satisfactory due to the random circulation of the pulp in the cooker as the heating process is carried on.

All moisture evaporation will occur due to direct heating of the portion of the batch in contact with the heating coils. When any part of the batch receives sufficient heat from the coils to turn the water portion thereof to steam, this part will be concentrated. However, if this part of the batch is moved out of contact with the coil before it is partially converted to steam, it will give up its acquired heat to the cooler part of the batch surrounding it. This process will continue until the temperature of the whole batch is brought to a sufiiciently high degree so that little time is required for conversion to steam after a portion of the batch again comes into contact with the heating coils. In the process, the various parts of the batch will receive heat as they come into contact with the coils and will then lose this heat to the surrounding parts of the batch, Without evaporation taking place. The desirable situation is to have the batch receive the heat required for evaporation in the shortest time since the degree of discoloration of the batch depends both on the temperature and the length of time that the product remains at this temperature.

In a continuous system, the random circulation of the batch in the cooker causes the discharge to be comprised of undercooked, properly-cooked and over-cooked pulp. Some of the properly concentrated pulp is fed back into the cooker instead of being removed therefrom, where it repeats the heating and concentrating stages. As the pulp again stands by in the cooker, it receives heat without being concentrated, until it again comes into contact with the heating coils. The situation is made worse by the continual addition of the cold pulp, since it is then impossible to have the whole batch at the same temperature. The chilling effect of the newly entering pulp causes the heated pulp already in the cooker to cool, requiring the temperature thereof to be again raised to the boiling point. Again, this repeated heating, cooling and heating increases the susceptibility of the product to damage.

The present apparatus overcomes the above problems by allowing a method to be carried out for uniformly heating and concentrating the tomato products wherein the pulp is confined to a thin flow path in the cooker and wherein the pulp is uniformly heated as it flows by gravity in a thin layer through this flow path. The thinness of the layer of pulp prevents random circulation of the pulp in the How path, prevents comrningling of the cooked pulp with newly added pulp and prevents the standby of pulp in the cooker whereby the pulp would continue to be heated Without being evaporated. In addition, with a definite flow path established, it becomes much easier to arrange the heating coils such that uniform heating can be accomplished, and such that a lower coil temperature may be used in comparison to the coil temperatures necessary when the pulp circulates at random.

In my prior application, Serial No. 696,707, filed November 15, 1957, entitled Method of Concentrating Food Products, and now abandoned, I disclosed an apparatus in which tomato pulp flowed continuously through a cooker. However, it has been found that the various chambers through which the pulp flowed were too large in volume. As a consequence, the pulp moved randomly in each chamber rather than uniformly through the chambers. This was particularly so in the chambers wherein the pulp flowed upwardly. Even though the input and discharge was at a constant rate, the amount of time and the amount of heating received by each por tion of the batch varied widely.

In the present apparatus, the concept of providing a continuous flow from chamber to chamber is retained, but the apparatus has been designed to provide for more uniformity in the heating of all portions of the batch.

The primary object of the invention is to provide a device for concentrating fluid-like food products wherein the product is flowed by gravity continuously through the device and wherein heating coils are used to heat the batch uniformly to drive out a desired percentage of water.

A further object of the invention is to provide apparatus for flowing tomato pulp in a thin wide flow path and for heating the pulp uniformly as it flows in such flow path.

A further object is to provide a tomato pulp concentration in which deleterious standby of the product in the cooker, wherein the pulp is heated without concentrating, is avoided.

Another object of the invention is to provide a plurality of side-byside troughs and means to flow tomato pulp through each trough in a relatively thin flow path so that the pulp overflows from one trough to another without backflow, and in which heating coils are moved against the flow of pulp to heat the pulp and concentrate it.

Other objects and advantages will become apparent in the course of the following detailed description.

In the drawings, forming a part of this application,

and in which like parts are designated by like reference numerals throughout the same,

FIG. 1 is a front elevational view of a food product concentrator, constructed in accordance with the invention, with portions cut away shown in section.

FIG. 2 is a sectional view of the device of FIG. 1, taken on line 2-2 thereof, and with parts shown in plan.

Referring now to the drawings, the concentrator, or cooker, comprises a generally rectangular tank having opposed side walls 11 and 12 and end walls 13 and 14. The bottom of the tank is formed by a plurality of generally U-shaped troughs 1'6, 17, 18 and 19 disposed in side-to-side relationship and extending between the end walls 13 and 14 of the tank.

Trough 16 has two side Walls, one being formed by the tank side wall 11 and the other side wall 21 being a common wall to both troughs 16 and 17. Similarly trough side Wall 22 is common to troughs 17 and 18 and trough side wall 23 is common to troughs 18 and 19. The other side wall of trough 19 is formed by the lower portion 24 of tank side wall 12.

A steam supply pipe 26 is connected through a rotatable packing gland 27 to the heating coil 28 which extends helically through trough 16. Coil 28 connects through a rotatable packing gland 29 to a steam return line 31. Similarly, heating coils 32, 33 and 34 are connected to and between steam lines 26 and 31.

The heating coil 28 is adapted to be rotated in trough 16 by motor 36 having a chain drive connection 37 to the heating coil. Similarly, heating coils 32, 3'3 and 34 are provided with power drive units 36 for independent rotation thereof. Although it is preferable to rotate the different heating coils independently, it is to be realized that they could all be connected for rotation from a single power source, if desired.

The trough 16 has the central portion thereof blocked out by means of an enclosed cylindrical drum 38 ex tending longitudinally of the trough and generally from end to end of the trough. The drum 38 is fixed to coil 28 by spacers 39 so that the drum is generally coaxial to the coil 28. Similarly, drums 42, 43 and 44 are disposed in troughs 17, 18 and 19 and are secured to the heating coils 32, 33 and 34, respectively. These drums have their lower surface generally complementary to and spaced from the bottoms of the troughs and act as fluid guiding members by confining fiuid flow to a relatively thin flow path between the drums and the troughs.

Partition 46 is disposed in trough 16 adjacent the side wall 21 thereof and extends between the tank end walls 13 and 14. The partition extends downwardly from above the upper edge of trough wall 21 to near the bottom of the trough. The partition 46 is generally complementary to the shape of the trough wall 21 adjacent thereto and is generally uniformly spaced therefrom.

Similarly, partitions 47, 48 and 49 extend downwardly into troughs 17, 18 and 19 respectively.

An inlet pipe 51 extends through tank side wall 11 for the introduction of tomato pulp from reservoir 52 into trough 16. The inlet flow can be controlled, as by valve 53.

An overflow, or discharge pipe 56 is connected to gutter 57 which extends between tank side walls 13 and 14 adjacent trough wall 24. The bottom 58 of the gutter 57 preferably slants downwardly from the ends of the gutter to the overflow pipe 56 so that the overflow of pulp at any point along trough walls 24 will flow by gravity in gutter 57 to the overflow pipe.

A cover '61 fits over the tank 10 and is sealed thereto by suitable means (not shown). An outlet 62, provided in the cover, enables the steam from the interior of the tank to escape to atmosphere. In addition to operation at atmospheric pressure, the outlet 62 may be connected to a super-atmospheric pressure source or a sub-atmospheric pressure source so that the device may be operated under pressure or vacuum conditions, as desired. A manhole 63 is provided in cover 61 for inspection and cleaning purposes.

Each trough is provided with a drain cock 64 enabling the trough to be individually emptied.

In the operation of the device, tomato pulp 65 is continuously fed into trough 16 from reservoir 52. As the pulp fills trough 16, it will also rise in the space between partition 46 and trough wall 21 until the pulp in trough 16 reaches the height of trough wall 21. Additional pulp entering trough 16 then causes an overflow into trough 17, causing this trough to fill. In due course, all troughs will be filled, with the pulp overflowing from trough 19 over wall 24 to the discharge pipe 56. The pulp will then be conducted by this pipe to any desired point in the cannery.

Since all of the troughs 16, 17, 18 and 19 are open at their upper ends to a common pressure, the continuous addition of pulp to the device through inlet pipe 51 will cause the pulp to flow downwardly in each trough, forcing an equal amount upwardly in the relatively thin spaces between the partitions and the trough side walls to overflow into the next trough. The enclosed drums in each trough will confine the pulp to the relatively thin space between the drums and the trough walls so that the pulp is confined to relatively thin flow paths through out its passage through the device.

As the pulp progresses by gravity flow through the device, it is heated by the coils 28, 32, 33 and 34, which are disposed in the flow paths of the pulp, to drive off water from the pulp. In order to heat the pulp uniformly, the coils are rotated by motors 36 in a clockwise direction (as seen in FIG. 1), counter to the flow of pulp in the troughs. This counter-rotation of the coils, together with their helical disposition in the troughs causes some turbulence in the pulp and allows much more of the pulp to come into actual contact with the heating coils. With the relatively thin flow paths, and with the slight agitation of the pulp by the counter rotating heating coils it becomes possible to use a lower temperature in the coils, greatly reducing the danger of overheating the pulp and preventing undesirable discoloration of the tomato pulp.

The height of the trough walls 21, 22, 23 and 24 maintains the height of the pulp in each trough above the top of the heating coils. Otherwise, the upper portions of the coils would extend above the surface of the pulp and the pulp adhering to the coils at those points would burn onto the coils.

The thinness of the flow paths greatly reduces any tendency of the pulp to circulate at random in the troughs and thus also prevents any backflow of pulp from one trough to another. This is particularly so in the thin flow spaces wherein the pulp flows upwardly from the bottom of one trough into the next trough. If the space for the upward flow path has a thicker crosssection (or a greater volume), then the pulp will be more susceptible to eddy currents and a part of the pulp may flow back down into the trough from which it had come.

Although most of the pulp in a trough will flow through the trough in a counterclockwise direction, as seen in FIG. 1, there will be some of the pulp flowing over the top of the drums and down the right sides of the troughs. The clockwise rotation of the drum and coils prevents these pockets of pulp from remaining motionless in the troughs, since the rotation of the drum and coil will induce a clockwise movement in the pulp, moving it down to the outlets at the bottom of the partitions. Thus, this portion of the pulp is prevented from being in contact with the heating coils for an undue length of time.

The amount of concentration of the discharged pulp is determined chiefly by the total amount of heat imparted to the pulp as it passes through the cooker. The greater the amount of heat, the greater will be the evaporation of the water in the pulp, and the more concentrated the discharged product will be. The principal control over the amount of concentration is the variation of the rate of flow of the pulp into the cooker, for this will determine the length of time that the pulp remains in heat exchange with the heating coils.

The amount of concentration can also be varied by varying the temperature of the steam in the steam supply line 26. However, this method is not as desirable since it is preferable to use as low a temperature steam as possible in order to avoid overheating of the pulp and consequent possible discoloration thereof.

As an illustration of the operation of a commercial embodiment of the invention, each heating coil has approximately 90 square fee-t of heating surface and is supplied with steam at 40 pounds pressure. A flow rate of 140 gallons per minute through the four troughs will concentrate a tomato pu-lp from an initial concentration of 5.5% solids by weight to approximately solids by weight. The heating coils are rotated at 3545 r.p.m. during operation. It is of course to be realized that these figures are illustrative of the operation, and are not to be considered as critical.

It is further to be realized that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same, and that various changes may be made in the shape, size and arrangement of parts without departing from the spirit of the invention or the scope of the attached claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. Apparatus for concentrating a fluid-like food product comprising an elongated U-shaped trough having side walls, a closed cylindrical drum disposed longitudinally in said trough, a heating coil disposed around said drum for rotation in said trough, a partition member extending from end to end of said trough adjacent a side wall of said trough, said partition member extending downwardly from above the trough side Wall and terminating near the bottom of said trough, an inlet into said trough for entry of a fluid-like food product into said trough, and an outlet from said trough arranged to receive the overflow of said product from said trough from between the partition and side wall adjacent thereto, said heating coil being disposed in said trough completely below the upper levels of said side walls.

2. Apparatus for concentrating a fluid-like food product comprising an elongated U-shaped trough having side walls, a closed cylindrical drum disposed longitudinally in said trough from end to end thereof, a heating coil disposed helically around said drum and completely below the upper levels of said side walls, a partition member extending from end to end of said trough adjacent a side wall of said trough, said partition member extending downwardly from above the trough side wall and terminating near the bottom of said trough, said partition being generally uniformly closely spaced from the trough side wall adjacent thereto, an inlet into said trough for entry of a fluid-like food product into said trough, an outlet from said trough arranged to receive the overflow of said product from said trough from between the par-tition and side wall thereof, and means for rotating the heating coil in said trough in a direction opposite to the direction of flow of the food product through said trough.

3. Apparatus for concentrating a fluid-like food product comprising a generally rectangular tank having a plurality of elongated U-shaped troughs extending in side-to-side relationship with one another between opposite ends of said tank, each of said troughs having first and second opposed side walls with the second side wall of each trough being the first side wall of the succeeding trough, a fluid guiding member disposed longitudinally in each trough from end to end thereof and having a lower surface generally complementary to and spaced from the bottom of said trough, a heating coil disposed in the spaces between each trough and the fluid guiding member therein, each of said coils being completely disposed below the upper levels of the side walls of the trough within which said coil is disposed, a plurality of partition members extending from end to end of said tank with one partition member being disposed in each trough adjacent the second side wall thereof, said partition members extending downwardly from above the trough side walls to between said fluid guiding members and said troughs, each of said partitions being generally uniformly closely spaced from the trough side wall adjacent thereto, said tank having an inlet therethrough into the first of said troughs for entry of a fluid-like food product into said trough, said partitions being adjacent the particular side wall of each trough such that the continual flow of product through said inlet into said tank will cause the product to flow out of each trough between the partition member and side wall thereof to spill over into the next trough adjacent thereto, said tank having an outlet from the last of said troughs arranged to receive the flow of said product from said last mentioned trough from between the partition and side wall thereof.

4. Apparatus for concentrating a fluid-like food product comprising a plurality of elongated U-shaped troughs disposed in side-to-side relationship with one another, each of said troughs having first and second opposed side walls with the second side wall of each trough being the first side wall of the succeeding trough, a closed cylindrical drumdisposed longitudinally in each trough, a heating coil disposed around each drum and disposed completely below the upper levels of the side walls of the trough within which said coil is disposed, a plurality of partition members extending from end to end of said troughs with one partition member being disposed in each trough adjacent the second side wall thereof, said partition members extending downwardly from above the trough side walls and terminating near the bottoms of said troughs, an inlet into the first of said troughs for entry of a fluid-like food product into said trough, and an outlet from the last of said troughs arranged to recei-ve the overflow of said product from said trough from between the partition and side wall thereof.

5. Apparatus for concentrating a fluid-like food product comprising a generally rectangular tank having a plurality of elongated U-shaped troughs extending in side-to-side relationship with one another between opposite ends of said tank, each of said troughs having first and second opposed side walls with the second side wall of each trough being the first side Wall of the succeeding trough, a closed cylindrical drum disposed longitudinally in each trough from end to end thereof, a heating coil disposed around each drum in the space between the drum and the trough and disposed completely below the upper levels of the side walls of the trough within which said coil is disposed, a plurality of partition members extending from end to end of said tank with one partition member being disposed in each trough adjacent the second side wall thereof, said partition members extending downwardly from above the trough side walls and terminating near the bottoms of said troughs, said tank having an inlet therethrough into one of said troughs for entry of a fluid-like food product into said trough, said partitions being adjacent the particular side wall of each trough such that the continual flow of product through said inlet into said tank will cause the product to flow out of each trough between the partition member and said wall thereof to spill over into the next trough adjacent thereto, said tank having an outlet from the last of said troughs arranged to receive the flow of said product from said trough from between the partition and side wall thereof, and means for rotating the heating coils in each trough in a direction opposite to the direction of flow of the food product through said trough.

6. Apparatus for concentrating a fluid-like food prod- 7 net comprising a generally rectangular tank having a plurality of elongated U-shaped troughs extending in :side-to-side relationship with one another between opposite ends of said tank, each of said troughs having first and second opposed side walls with the second side wall of each trough being the first side wall of the succeeding trough, a closed cylindrical drum disposed longitudinally in each trough from end to end thereof, a heating coil disposed helically around each drum in the space between the dnlm and the trough and disposed completely below the upper levels of the side walls of the trough within which said coil is disposed, a plurality of partitio'n members extending from end to end of said tank with one partition member being disposed in each trough adjacent the second side wall thereof, said partition members extending downwardly from above the trough side walls and terminating near the bottoms of said troughs, each of said partitions being generally uniformly closely spaced from the trough side wall adjacent thereto, said tank having an inlet therethrough into one of said troughs for entry of a fluid-like food product into said trough, said partition's being adjacent the particular side wall of 'each trough such that the continual flow of product through said inlet into said tank will cause the product to flow out of each trough between the partition member and side wall thereof to spill over into the next trough adjacent thereto, said tank having an outlet from another of said troughs arranged to receive the overflow of said product from said trough from between the partition and side wall thereof, means for rotating the heating coils in each trough in a direction opposite to the direction of flow of the food product through said trough, a hood enclosing the upper end of said tank, and means to connect said tank to a source of pressure.

References Cited in the file of this patent UNITED STATES PATENTS 642,620 Mather Feb. 6, 1900 990,352 Grell Mar. 25, 1911 1,366,642 Evans Jan. 25-, 1921 1,380,689 Thiele June 7, 1921 1,919,400 Stokes July 25, 1933 2,034,969 Behrens Mar. 24, 1936 2,782,843 Rodenacker Feb. 26, 1957 FOREIGN PATENTS 415,904 Germany July 3, 1925 496,193 Great Britain NOV. 25, 1938 924,027 Germany Feb. 24, 1955 

